Napier covers an area of 10,300 hectares and has an approximate total population of 55,500 people living in 21,215 dwellings.
The City has two district areas in terms of development, one being urban, and the other rural. The urban area covers 3,380 hectares with the balance classified as rural. The urban population is 51,890 and the rural population 3,610. Of the 21,215 dwellings in Napier, 1,272 are located in the rural area.
All of the urban area has a reticulated water supply. Some properties in Taradale still use their own private well supply, however, the City's reticulated supply is available.
A small number of rural properties adjacent to the urban reticulation system have connections to the urban supply for domestic use.
The following consumption figures are based on consumption for the year 1 July 2002 to 30 June 2003.
|Total Annual Consumption||10,500,000m³|
|Approx Peak Day Consumption||50,000m³|
|Average Daily Consumption||29,000m³|
|Approximate Minimum Day Consumption||22,000m³|
Source of Water
10 wells draw water from the artesian aquifer beneath the City and provide all of Napier's water. The aquifer is part of the Heretaunga Plains underground water system that is administered by the Hawkes Bay Regional Council.
The depth of the wells range from approximately 40 to 100 metres, with the diameters ranging from 200 to 300 millimetres. The aquifer has a static head ranging from approximately 1 to 6 metres above ground level.
There are 18 pump stations servicing the City, with a total of 33 pumps. 10 stations are source stations (i.e. they draw water from the aquifer); the other eight stations are booster stations that pump water between reservoir systems.
The City has approximately 400 kilometres of mains ranging in diameter from 40 to 450 millimetres. The older areas of the City are reticulated with cast iron, and in some cases steel pipes, although these are gradually being replaced as they become uneconomical to maintain. The newer areas were reticulated with asbestos cement pipes until 1986, after which uPVC was chosen as the preferred material.
- The City has 2 main reservoir systems to store water for peak demands. They are the Thompson Road system and the Enfield Road system.
- The Thompson Road system serves the Bluff Hill area, and provides back-up supply to the Central Business District and Ahuriri area. The top water level is 99 metres above mean sea level, with a net capacity of 7,075m³ .
- The balance of the City is served by the Enfield Road reservoir system, which includes the Taradale Reservoir. This is the principal system for the City supplying the bulk of the population. The top water levels of the 2 reservoirs are at 51.5 metres above mean sea level and have a combined capacity of 20,240m³ .
- Three small reticulation systems provide water to residents on the hills of Taradale. These systems have small reservoirs and use booster pumps to pump water from the Enfield system.
- Water is supplied to residents at the top of Bluff Hill adjacent to Thompson Road reservoir using a variable speed pumping system to meet demand and maintain a constant pressure. This system pumps water directly from the Thompson Road reservoir.
- Three reservoirs serve the Bay View area. Water is supplied to Bay View from a well located in Meeanee and also from a booster pump station that draws water from the Napier water supply system.
All pump stations and reservoirs are linked to a Programmable Logic Controller (PLC) by radio telemetry for centralised control and alarm monitoring.
The PLC monitors the levels of reservoirs and automatically controls pumps as levels vary. If pumps fail or reservoir levels reach low level or overflow conditions, an alarm is generated by the PLC to alert staff. Automatic control of the system by the PLC can be overridden to allow staff to control the pumps if required. After hours, staff can communicate with the PLC using a remote terminal connected to a telephone to check the status of the system, and to control pumps.
Napier is fortunate in having a supply of water that can be used directly without the need for treatment.
The artesian supply is free from bacteriological and viral contamination, and is also free from the cysts that cause Giardia Lamblia and Cryptosporidiosis. This means that filtration, chemical treatment such as disinfection, and other forms of treatment, are not required, all of which would add costs to the consumer.
Bacteriological and chemical tests are carried out on samples taken from pump stations, reservoirs, and randomly from the reticulation on a regular basis to ensure that the system remains free from contamination in accordance with the Drinking Water Standards of New Zealand 2005.
Napier has never fluoridated its water supply and there are no plans to.